Moveable mask after blur filter... Stops moving!

Okay, I have a bunch of pairs of images. And I have a custom cursor with a mask inside that displays alternate versions of the images by being a mask to them. All works beautifully, until I use a blurFilter transition to fade between one image to the next.

All the images get loaded before the mask is set, and I’ve narrowed the problem to the blur filter. What’s happening, is that once I apply the blur filter, the mask seems to stop moving. The movieClip that it’s nested in moves fine though. Basically, for a few seconds after I apply the blur, the mask works, but then it just stops moving and only displays the one location where it was when it stopped moving. If I don’t apply the blur filter everything works fine. No problems at all…

Anyone encountered this before or have any thoughts? I’m stumped…